Conventional conveyors used in food processing typically include a plurality of wide, flat panel-like conveyor flights flexibly interconnected at opposite sides by a pair of chains to form an endless loop. These flights together define a long, wide, flat belt upon which the product is supported for drying, blanching, spraying and the like. Rows of apertures or slots may be provided in individual supporting surfaces of the flights to drain off excessive moisture or facilitate the flow of air therethrough. The conveyor is supported at its ends by sprockets which engage the chains and at its mid-section by side runners or rails.
In some food processing applications, such as the water blanching of potato strips, it is frequently desirable to submerge the product in hot water by running the belt down into, then up out of, a hot water pool.
The foregoing conveyor system has several significant disadvantages. First, the wide panel-like flights are structurally very weak and require considerable reinforcing to prevent transverse bending due to their own weight and the weight of the supported product. This problem is aggravated by the numerous slots or apertures in the supporting surfaces of the flights which further weaken the transverse strength of the flights. In fact, the edge portions of the flights cannot be perforated without seriously affecting the structural integrity of the flights. As a subsidiary problem, the reinforcing members required make cleaning of the apparatus difficult.
Second, the conveyed product is off-loaded non-uniformly because the product tends to stay on the surface of the underlying flight as it moves around a sprocket-supported end portion of the conveyor until the flight pivots to a critical point when the entire batch of product slides off the flight.
Third, it is difficult to scrape all the remaining product adhered to the flights therefrom (after off-loading) because a scraping device, or doctor blade, typically used for this function is pivoted at one end to provide clearance for the leading and trailing edges of the flights. Consequently, the blade is constantly pivoting back and forth to clear such edges and, therefore, does not maintain continuous contact with the flights. Adhered product which is not removed on the first pass must be removed either by expensive additional scraping equipment underlying the conveyor or by the primary scraping device during a subsequent pass after the product has been over-cooked or over-dried.
Finally, because the product will slide on steeply inclined surfaces, the product can be raised and lowered only by a relatively long, gently sloping conveyor path, making the conveyor relatively expensive.
Accordingly, there is a need for a simple, inexpensive conveyor that resists transverse bending stresses without requiring extensive reinforcing members, promotes uniform off-loading of the product, and is capable of conveying the product up and down relatively steep grades.
It is therefore one object of the invention to provide a conveying apparatus that resists transverse bending stresses without requiring extensive reinforcing members.
A second object of the invention is to provide a conveying apparatus as aforesaid having flights that can be perforated over their full width without substantially affecting the structural integrity thereof.
A further object of the invention is to provide a conveying apparatus as aforesaid that promotes uniform off-loading of the product.
Another object of the invention is to provide a conveying apparatus as aforesaid that facilitates continuous contact of the flights with scraping equipment used to remove adhered product therefrom, thereby virtually to eliminate overcooking or over-drying of the product caused by multiple passes of the product through blanching or drying equipment.
A still further object of the invention is to provide a conveying apparatus as aforesaid that does not require expensive, additional scraping equipment underlying the conveyor to scrape away unremoved product.
Yet another object of the invention is to provide a conveying apparatus as aforesaid that is capable of conveying product up and down relatively steep grades, thereby to shorten the conveyor length required to raise and lower the product a given height and to reduce the cost of the apparatus.
Another object of the invention is to provide conveying apparatus as aforesaid that is easy to clean.
Other objects and advantages of the invention will become apparent from the drawings and following detailed description.